1. Field of the Invention
The present invention relates to a decoding device, a method for controlling the decoding device, and an image forming apparatus.
2. Description of the Related Art
Conventionally, an image forming apparatus, such as an ink-jet printer or a laser printer, usually performs a compression process on data for forming an image on a recording medium such as paper (hereinafter, referred to as a “sheet”) because the data is tens to hundreds of megabytes in size. Therefore, at the time of image formation, the image forming apparatus needs to sequentially expand the compressed data and output this expanded data to a recording head or the like.
In the case of color printing, compressed data input through multiple channels needs to be expanded with respect to each color. The following are known as conventional technologies for expanding compressed data input through multiple channels in a time-sharing manner: Japanese Patent Application Laid-open No. 2005-96343 and Japanese Patent Application Laid-open No. H11-177831. In the technology disclosed in Japanese Patent Application Laid-open No. 2005-96343, compressed data input through multiple channels is expanded in a time-sharing manner by the use of one expansion unit and channel-specific buffers. In the technology disclosed in Japanese Patent Application Laid-open No. H11-177831, dummy data is added to data before being compressed, and, at the time of expansion, the dummy data is thrown away after being read; thus, large-capacity buffers are not required for synchronizing the time to output expanded data expanded in a time-sharing manner.
However, in the above conventional technologies, it is necessary to provide a large-capacity buffer capable of storing expanded data obtained by expanding compressed data input through the corresponding channel. Furthermore, the addition of dummy data to data before being compressed leads to a decrease in the compression efficiency of the compressed data.